Telephone-exchange system.



F. N. REEVES.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAB..20,1912.

Patented Sept. 8, 1914.

2 SHEETS-SHEET 1.

l/V/7nessas; Jj! 9i I/ P. N. REEVES.

TELEPHoNE ExcHANen SYSTEM.

APPLICATION FILED MAR.20, 1912.

Patented Sept. 8, 1914.

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UNITED simens rafrnn'r oFFron.

FRANK N. REEVES, F NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY.

OF NEW YORK, N. Y., A CORPORATION 0F ILLINOIS.'

TELEPHONEEXCHANGE vS'YSlIElilI.

Specification of Letters Patent.

T0 all'l 'whom 'it may conf-ern `lle it known that l, FnA'xK'N. REEVES, a citizen of the United States, residing at New York. in. the county of New York and State o'f New York, have invented a certain new and useful Improvement in 'Telephone-Exchange, Systems, of which the'- following is a fullyeiear, concise, and 'exact description. This invention relates to telephone. i0 change systems of the typein which automatic switches or selec'tors'are employed for the interconnection of telephone lines, and it has'for its object in general, to provide improved means associated Awith .the switch' 'L5 .mechanisms thereof for governing 4their op- 1 eration. r IAccording to a well-kno`un methodof operation!,inl automatic and semi-automatic telf eph'one Qefnfehange systems, a series of selector s,\v tcli' meq'hanismszare arranged' and contlldto operate snceessivel y in making any` "desired nonnetion, each `of said switch mech- 'anisms` ,by 'meansv ofl suitable controlling apparat.us,'heingfcau$d first `to associate itself 'with a- .particular one of a plurality of groups,oflinesand then to operate ante-'2 VJllllic2-1lly to .and make vconnection to an .idle linegof ,that group. These lines maybe; trunks adapted to,.fo rm intermediate connee-i tins between thasubscriberslines, or theyv may lbe a group of subscribers lines entendlngjgoai.singlesubstation, such as a private rganch exchange, They are ordinarily c onrnected to multlple terminals of aplurality .35..Qf Selectors.' f

Nif-There is usually' associated with each 'selgnectqr a deviceknown as a sequence switch function of which to establish in a' dene4 nite .order at successive stages the various 40`fei1cuits required to contrlthe operation of the' selector. vSuch a device is illustrated in United 'States patent to McBerty No. 1,009,023()- dated November 21. 1911. It is usualin such systems .tor the purpose of disestablishing partially completed connections toiprovide a device known as a Wipeolitvkei', wlhich,when depressed, operates to restore the apparatus to normal position without cstabljshin the connection initiated. :'.llhepl'esent invention relates more parti@ nlairly to' means associated withsnrh selectors .to .govern their operation in Finding; and nntking connection to idle lines. although 1t .maybe applied, if desired, to the control of the sequence switch and selector-be restore selectors for performing other operations than thatof connecting lines.

It 1s one ofthe objects of this invention to canse the selector as well as the sequence switch to be invariablfy restored to its nor` mal position whenthe Wipeout key is 0perated, in other words, to prevent a complete Y Patented Sept. 8, 1914. application mea March 2o, 1912. serial No. 684,946.

cuits closed alternatelyby eachother may Another feature ofthis invent-iorecte'd to the provision'ofv means'for p xgeuenb ing .the rselector from testingthdtiiunks which appear upon ca'se'thefyvipefout kefy is actuated priort'o the movement of the .i

brush carriage or duri-ng itsfjtraveh that -iS to` say, for preventlngvinl 'suclievei'lt .the

movement ot the brusl 1 carriage,froinbeingii arrestedby its test brush, eng aging-:in.idle1 trunkin its travel, tlfiis resulting a saving of time. In acoordancewith thlsfeatureof the invention, uponA the operation o ffthe A-wipe-.out key electromagnetic means is provided adapted to causejthe test circuit to ybe opened, and the selector and seqnencesvvitch to be restored.

A third. feature of theinvention the provision of means for v preventing inter` ference with existing calls. In the systen'x of this invention, an idle trunk is one union llntest terminal ofV Which-a certainelectrical rl-nnlition exists, and a busy trunk one upon the test terminal of which a difexentelectrical condition exists, a test relay operating' to seize the trnnkor not, according to tln.` electrical condition of its v test terminal. Upon seizing an idle trunlg'this test rela'v brings about a change in the electrical condition ot' its test terminal to cause it to test busy to other selectors, and it isessentnil thatihis. changed condition be maintained from thotinie the trunk which it re )resents andere is ser/.ed until it is released. To t is end,

vided to inform the operator of this, or the calling subscriber himself may bring it t0 her attention. In the present system, the idle condition of a trunk is indicated by-a certain potential of the test terminal to which. the test relay is responsive and the busy condition by a lower potential to which the test relay is unresponsive. The test re lay may have two windings, one of high resistance ineludedin circuit during the testing operation and one of low resistance included in circuit in shunt of the high resist ance path when connection is made with an idle trunk to reduce the potential upon its test terminal to cause itto test busy to other selectors. "lhe motor magnet which actuates the selector may be excited by the denergization of a relay in this low resistance eircuit so that in case the low resistancepath is subsequently opened during the pendency of a conversation, the circuit of the selector motor magnet is closed which restores the selector and its associated sequence. switch to normal position.

Still another feature of the system concerns thereduction of errors on the part of the automatic switching mechanism in setting up calls, and the-prevention of interference. with existing calls. In powerdriven selectors wherein the power is cut ofi` from the selector when the test brush encounters a test terminal of an idle trunk, it will be appreciated that due to inertia, the brush carriage will frequently overjump the desired set of terminals if the trunkbecomes idle and the power is cut off while the test brush is traveling over the latter portion of the face of its test terminal. Consideration of the mechanical relation between the test contacts and their associated line contacts appearing in a terminal board of this type will malte this clear.

It will be noted that the test brush and its associated line brushes of any set engage the edge of the fixed terminals at substantially the same instant, -both the brushes and terminals being vertically alined. NowA assume that `the trunk represented by the terminals over which a set of threebrushes is traveling becomes idle while the brushes are traversirig the latter part of the face of the fixed terminals. The 'test relay will, of course, respond and cut off the power; too late how- Y ever,.to prevent the inertia of the brus can riage from causing it to overjump the desired trunk. In accordance with this feature of the invention, Iso arrange the apparatus and circuits that the means neces# sary to arrest the travel of the brush carriage may be actuated only in case a sufiicient margin exists to permitthe carriage to be arrested on the terminalsv which initiated the arresting movement. One way of accomplishing this result is to -divide the duration of travel of a test brush over a test terminal into two periodsthgY first of which may be called the safe and the latter the danger period, and so arrange the test circuit which controls themovement of the brush carriage that if it is not closed during the safe period, it cannot be closed by any change in theelcctrical condition of that test terminal during the danger period, that is, while the test brush is engaging its latter part, but instead, the carriage will move on and not be arrested unt-il its test brush contacts with a test terminal whose trunk was rendered idle at least when the test brush travels over the initial part thereof.

For the purpose of illustrating the invention, there are shown in the drawings which accompany this application a single selector and the apparatus associated' therewith for governing its operation. It will be understood that in the construction of a large telephone exchange system there would be several such selectors operated successively in thc`establishing of any one connection. The invention herein described and claimed may be applied to the control of any one of such selectors. The one shown is an office `switch and is theseeond of a series in an actual exchange. Y

In the drawings-Figure 1 shows the cirsov cuits and apparatus which are directly associated with a single vselector switch mechanism; Fig. 2 shows the circuits of a suitable controlling apparatus connected over. trunk wires to the selector, the two figures when placed side by side, No. 2 to the left of No. 1, forming a complete circuit diagram of 'the selector and its controlling apparatus.

In the form of automatic switch shown on Fig. 1, the switch carriage or movable element is provided with a number oft' sets of multiple brushes, any particular set ofwhich may be selected for service and the switch carriage then advanced over a series of sets of terminals until the selected brushes are brought intoengagement with the terminals of an idle line.

The switch carriage or brush-carrying member is of the rotary type, the frame -21 of which is mounted upon a central standardor shaft 22. At the outer end of the frame a number of setsof contact brushes 28, 24, 25 are pivotally mounted upon but insulated from a rod 2G, and from each other, in position to sweep over sets/of line terminals'27, 28, 29. The brushes have inwardly extending arms 30, bearing against Latches 32, one for each set of three brushes,

are pivotallv mounted upon a rod 33 and arranged to normally hold the brushes from being rocked outwardly into line with the stationary terminals. Bearing against the inner ends of the latches are springs 34 which hold the latches firmly against a 4stop rod 36. This sto rod 36 serves to prevent the latches from eing moved forward too far after he brushed hz, Stop fm; T35 sex'wi tu E movement. .:yf the; hzxzi are v' uffaaia4 The Ua@ l @es n :zo E thi mused im stop with the sawctw! WMM The circuit umngement, ns wil mutui-t with some sm, Hf' simu-muy im' appear, such that the nmhve sawing; the huub earring@ am es, n@ bf only. The connection with contact 60 is intermittent, this Contact being made when the -arm 5G is lifted by each tooth of the cam.

The motor mechanism for causing rota-y tion of the brush carriage comprises an annular iron friction disk 61 flexibly mounted at the lower end of the spindle Q2, an electromagnet 62 which may be fixed in any snitable manner to'the trame, and a constantly rotating shaft (13 carrying an iron driving roller 64. 'lhe disk 61, roller Gt and that part of the shaft 63 which extends through the center of the eloctromagnet (SQ form the magnetic, circuit of the electromagnet 62. llVhen therefore current is passed through the winding of the magnet, the roller (S4 attracts the disk 61 and causes the latter to rotate by frictional contact therewith. A holding clectromagnet 65 having a pole piece (it extendinof upwardly beneath the disk G1 is adapted` when current is passed through its winding` to engage the disk and hold it from movement. The power shaft Gil is extended as shown in the drawing to carry a flexibly mounted driving disk 70. which is adapted to engage a roller G7 carried by the spindle 40. An electromagnet (i8 controls the engagement et' disk 70 and roller 67 in the same manner that the electromagnet 62 controls the engagement ot disk 61 and roller 64, These devices are in tact electromagnetic clutches. one to cause movement ot the brush carriage and the other to cause movement of the brush selector.

'lhe complete selector switch mechanism is net shown in the drawings, but the elements thereof appear 'in their proper relation to one rmother so as to make clear the manner in which the mechanism operates to intel` connect lines. There may be as many sets of brushes and stationary terminals as dcsired. For example. the switch mechanism may, as a whole, have ten sets ot" three brushes each and two hundred sets ot tixed terminals arranged in ten levels ot' twenty sets each. For simplicity in the diagram there an` shown only two sets oi brushes, the eighth and ninth counting t'rom the top down. and six sets ot' -stationary terminals in two levels corresponding' to the two sets of brushes shown.

Home ot thc circuits ot' the selectors are controlled by sequence switches and there is ordinarily one such sequence switch tor each selector. ln general. the function ot' the sequence switch is te move from normal position upon the operation ot' the sender or controller, and to establish in a definite order at successive stages ot' the operation the various circuits required to bring i-nto service various devices or parts in proper sequence. The sequence switch consists in its elements of a movable switch operating member, a number of circuit changers actuated in sequence as said member is moved from one position to another, an electromagnet, and motor mechanism operated or controlled by said magnet for advancing said movable member. In each position to which a mov able member of the sequence switch is advanced, a circuit or set of circuits is established by which a given operation of the device under control is made possible, and at the same time another circuit is 'placed in a. condition whereby the motor magnet of the sequence switch may be subsequently actuated so that the sequence switch will then be automatically advanced to the next. position, until a new set oli circuits is established, bringing about a. new operation or electrical condition of the device or devices under control,` and so on, and finally upon the disestablishment of a connection, is returned to its normal position ready for service in establishing another connection.

The switch springs of the sequence switch are not shown in their actual arrangement, but are so located as to give the clearest arrangement of circuits. The positions of the rotary element of the scqnenceswitclrin which any of its contacts are closed are in'- dicated by the numbers placed adjacent such contacts, each contact being open in all positions except those indicated by the adjacent numbers. The sequence switch has a special contact governing the local or locking circuit of its motor magnet, such as contact 101, this contact being closed while the rotary element ofthe `sequence switch is in transit from one stopping position to tho next to insure that it will take the full move-- ment and not stop in intermediate positions. instead ot' designating the closed positions of the special contact 101 of the selector se qncnce switch, the onen positions are indicated and are placed on the opposite side of the Contact instead of adjacent to it. as in the other sequence switch contacts. For convenience in tracing the circuits separate batteries are shown at various points, but it will be, understood that these may, and where lorated in the same exchange would, in practice be one and the same battery.

suitable arrangement of controlling ap parat as for the selector mechanism is shown in Fig. 2. This apparatus comprises a series ot counting relays and a series of com trolling switches or keys. together with a stepping relay for operating the counting relays in succession to close contacts in cirenit-with svitehes or keys, and a cut-ofi' relay adapted when the circuit is closed simu]u taneously by one of the counting relays and the particular switch or key depressed, tog open the controlling circuit and stop the movement. of the selector. As shown, there are two series of counting relays. One series, compi-ning relays 201 t0 208 inclusive, :ire adapted refqwviively to close contarle` i201 Li L'l in eirvnil willi the keys -lil to ,255 and the cut-oil relu)Y 2:33. The olher vries of counting relays 211 to 218 inclusive Serve i'lw pnroe of closing ein-nite for relays 205 lo .bf und ure caused to o ernbe in alternare sneeesnion willi said re nys 201 lo t0n'. These two series of relays muy he exlenllell in an ohvion nmnner to include :my desired nninher. The stepping relay 224 is 1r-- ranged to he energized and llenergized inlerniiltenlly in the inevenient of the Selecting :is will he pregently explained. Upon the first energizntion, it closes its front eontneii which completes :i Circuit from hnllely through Contact 234, auxiliary counting relny 211 und. hack Contact of counting relay :01. nherenpun relay 211 is energized and loses i lurking eircuiz by Way of its front l'ontael 22% Relay 211 also cln'aes front eontnei. Q80.

ivry. commi $32, winding ol' winning relay iOl, haul( contini ol' thx: second auxiliaryl vonnling' reim' 2li. :inll freni' Contact 230 of the luist nnxilrlry relay ll. Relay 201 is Lherewpon nerfh neil und it, like relay 211,

vlo-lees a locking! rirruit, h v way of freni conl lzni. 201. before elnlefl, however, Said -tz 15 also in riz-mnt with the cutoff re- 'lieg' which hul heen depressed.

The :ieppisgj vl-ay 22% is included in l loop whirl! inn). loe zinoffinlml With the trunk line .mn'iflnl'tols Z-lf nini 123@ leading t() lie nrlellm' nil-"h ne l i n .in l.; .anllnhie :imleh 'conm is 23 :md lining proviilfil lor :linking the eosniection when il; is flerrml to anw lnk selerlor to perform a imrlivnhzi swirhingg' opernion. The trunk line Germinal/ors 2:55 :unl ill may have ns- ',1 hl-intel therewith :i third eonllnomr 939 inhidingy n reaiwtnnne 24() :ind a @Witch coninul Sill, which contant muy also he closed at or :ilonl the time the contarle 23T and' :258 nre (loeserl.

mnlrollul -in the operation ol' connecting rsnhfirlbers lines nml there are indilfatell in lhe trunk line conductors and the f associated conductor 2354) Witch contacts 2x42? Then when the stepping relay is deiieigizellt its, arnmlnre falle hack and closes il:` hawk contact, thereby con'ipleting a l rircuil lor ('onnling relay 201 hy Way of bat- ,3:5 i: inl he lirsly ol :i series of' controlling 24J; :unl 'lll whil-h inllil'zle eonlnrls of another fleet-rn' limi' :nur lie inkel-posed in the f firrni hen the seleiiing Operation which is nlronl l: ln; .lesiihell hiker; place.

Referring now io lig. l. which shows the nppznm'ils und elrvnii'f; nnsoeinlld with the Schreier swilrh mechnninn il` will lie noted ihnt the lrnnl; line ifnnihioinie 2.35 :and :236 :ire normally, finit is., 1

when the sequence connected through will; lll bottoni and 104 lop to iorin n loop enr, will: n line relay lil unil lmlm'y; who that the conductor 239 is eonnerteil l'hrmiggh an Milne-switch restorinf: relay 123 und n normal contact 105 of lhe selnienee m'iifh lo buttery. Contact springe lOEl bottoni nncl l-'l top ol the seqnenre riviteh are eli.: l in the first and sec- -onll positions, lherwl` while @outlets 1011` bottoni 12ml 103 lop thereof nre rlesed from the sixth to the lhirlei-nlh positions, inclnsive, to extend the rirlznit ol' ille trunk line lo lhe brushes 2B unil of the seleulor meehnnism. The line relnjyV hns u hol-ll contact und :A from: Contact whirl: :ne :nlnplell lo Coinplete Certain lornl circuiti; entering into the control ol the selector :nhl the :sequence swixches, a5 will preaenlly zippezir. The trunk of restoring relay lill le inlnplell when energized to close u locking :zii-enit for its winding by way of ils front ronzicl; 126 und batei'y and ai ilie saine time lo open Contact 129 in `(he motor ,magnet circuit el the sequence svi'ileli. The test Circuit terminates in the test brush 25 of the .seleeter switch nwchnnisin. Leading frmn the Sequence :milch rontfwl men'iher Siri inlzipled to be com ne ed in a tesi ref lll` i?, n izondnetor 93 which F; cfonneuled lo," wey ol' spring Si! lo the L'i'nlnl'l. lever lf ol lhe .switch Cs'xlringlc mec'hzinsnr libel: lhe .selector i5 in norninl posi'imn thi zwitlh lever resting in Conlziet will; die .fornnil atop plut-e 416, hut when the brush warring@ moves the brushes over lhe terminale. the linger T? of lever 43 nmkes Contact. niwmiltently with the teeth of plate 5() Whirl] in wnneeted to ground.

ll will lie noted thntn i'irl'nil through 'l may he chmul 1n nhnnl ol' lhe ,vil ,li in position selinux e li Sinin .if lli-s l'roni 'fw-nizw! n rirrilil for the holdmuol' may not hr the lirsl` nwilivh llo he wg?? nnigrwr :i circuit Swilfh wrlzlfl lll?. il' will he nOlC flint while the sequence switch is in its normal position, the circuit of its motor magnet 81 lnay be closed by way of the front contact of the line relay 121 and sequence switch contact 112 top; and that iu the second position, the circuit may be closed through the back contact of the line relay 121 and sequence switch contact 111 top. ln thc sccond position of the sequence switch, a circuit 111:11.Y also be closed for the motor magnet GS of the brush selector by way of'the front contact of the line relay and sequence switch contact 114 bottom. llihile the sequence switch is in positions 0 to 1 inclusive, a local circuit, is closed for this motor magnet 68 of the brush selector by way of sequence switch contact 114 top, and contact 59, this latter Contact being closed at all positions of the brush selector except normal,

It will be understood that thc primary function of the selector' switch shown in Fig. 1 is to interconnect lines for telephonie connnunication. As before stated, these lines may be trunks forming intermediate connecting links between the subscribers lines. Thus the conductors 235 and 230 may be extended to the left in Fig. 2 through suitable mechanism and conductors to a call ing subscribers line and conductors 140 and 141, which are connected to terminals'27 and 28 of the selector. may be extended to the right in Fig. 1 through suitable mechanism and conductors to a called subscribers line. Terminal 29 is connected through a resistance 142 to the free pole of the battery.y lt will be understood that the terminals 27, 2S and 29 of the selector switch may and would ordinarily be connected in multiple to the corresponding terminals of other selectors as shown.

For a clearer understanding of the dcscription, the following table of the positions of the sequence switch S1, controding thc selector, is given:

Position 1 Normal 2 Brush selection. 3 Trunk hunting. 5 Pren1ature return.

12l Talking.

16 Retnrn ot' selector.

the controlling apparatus into operative relation to the selector. These, and also contacts 232 and 234, may be operated manually, but preferably by a sequence switch mechanism of the same general construction as that associated with the selector. lt is merely for the sake of simplicity in the illustratiyc diagram that such sequence switch mechanif-m is omitted in Fig. 2. T-hc closing of contact 211 completes a circuit for the restoring relay 123 from ground, resistance 240, conductor 23. selector sequence switch contact 105 to battery. In operating, the restoring relay closes a locking circuit by way of its own front contact 126. It will thus be noted that the restoring relay will reinainienergized independently of the sequence switch contact 105, but that it is 11n- Ader the control of contact 241 so that whenever contact 241 is opened subsequently the restoring relay will be denergized. The closing of contacts 237 and 23S brings the stepping relay 224 into circuit with the line relay 121 over the following path: Battery, winding of relay 121, sequence switch spring 103 bottom, conductor 235. Contact 242, contact 23T, back contact of cut-off relay 223, the winding of stepping relay 224, contact 238, conductor 236, contact 243, and sequence Switch spring 104 top, to ground and back to battery. The closing of this circuit causes the energization of line relay 121 and stepping relay 224. Relay 224 closes a circuit for the first auxiliary counting relay 211 by way of battery, contact 234, winding of relay 211, back contact of the first counting relay 201 and front contact of the stepping relay 224 to ground. Relay 211 thereupon becomes locked in a circuit closed by way of its own front contact 229. It furthermore closes front contact 230 which places the first count-ing relay 201 in a partially completed circuit which may be subsequently made complete when the stepping relay is denergized and closes its back Contact. The energization of line relay 12]. causes the advance of the sequence switch from position 1, its normal position, to position 2. That is to say, the motor magnet 81 is brought into circuit by way of sequence switch` spring 112 top and the front contact of the line relay, and the sequence switch advances under the control of its special contact 101 to position 2 in which contact 112 top is open. y

In position 2, a circuit is closed for the motor magnet 68 of the brush selector by way of sequence switch spring 114 bottom, and

the front contact of'the line relay, Whereupon the shaft 40 is rotated and a series of contiitsare made between the arm 56 a d contact 60. A circuit is formed upon die making of such contact. from battery, line relay 121, sequence switch spring 116 and vlmnp; 1312 of tust remy A [um i wlny wli. 2 um" upon lim v nf a line which b w exist upon sa'n @mmm of sucent strength Herv. rgstame 142, said tes 2 und in ground afb 50 ruced including ,J L t0 (margze mfiatcy rrlnses its; Ming 134 by way unt uf Li e high ressian dusss ai contact 135, a m' the winmx-control rebeing hmtei however, ffm zwstance path to {if} through mnd :ctm' 93. f' r v we sxhuiing in rnddimx, to wmnsg' gum/nits n. How

whvh m mw.' mxmecwl in a msi cirl l) i) FLO completos a circuit for the motor magnet Rl, of the sequence switch by way of sequence witch sp1-ine 111 bottom, said contact and smpnuice switch contact 110. The sequence switch thereupon moves out of position 3 through )osition 5 and into position 13, it being under the controlot' the special switch Contact 101 in paving from position 5 to position 18. This is the talking position of hey ap )aratus in which the circuit of the trunk ine conductors 235 and 236 is closed to the brushes 23 and 24 by way of sequence switch spring 103 top and sequence switch spring 1.04 bottom. In position a local circuit for the motor magnet 68 of the brush vSlector is closed by way of'sequence switch spring 114 top, and the brush Selector, having no further function to perform with respect ltothe connection being made, is returned to its normal position. It is caused to sto) in its normal osition by the opening ot this local circuit at contact 59 when the free end of the arm 56 drops into the dee i notch in the star wheel 58.

` I lcui-ring to that portion of the operation of the selector when its test brush 25 has just reached the edge of a contact 2f) representing a busy line. Assume new that during its travel over the face of said terminal, the Line associated therewith becomes idle with -t ic resultant increase in potential caused by t e retrieval from the multiple test. contact 2,9 thereof at another selector of the low reinstance Winding 134 of a relay similar to niet of the Selector illustrated. n win be evident that since the test circuit leads by a conductor 93 through spring- 52, arm 13, finger 72 thereof, and finds ground by Way of the teeth on rack 50, that such increase in potential if occurring during the latter half period of the travel of the test brush over" the test terminal-that is, during the danger eriod, will not arrest the movement of the )rush carriage, it being borne in mind that during the entire period the finger 72 is traveling over one of the teeth of rack 50 the test brush 25 has traversed, but a portion of the corresponding test terminal 29; that is to say, the timing ot' the contact period of the finger 72 with any tooth is such that the test circuit can only be closed while the test brush 25' is in the 1i rst half or safe period of its contact with any test terminal 2) of` a trunk. This arrangement allows the motor control rclay 131 plenty of time to become energized and open the motor magnet circuit in time to insure the arresting of the selected set of brushes upon the set of fixed terminals which initiated the arresting movement.

Consider now that point in-thc .operation of the system when the test relay 13? is eX- cited by the test brush 29 engaging an idle trunk. and causing its armature to include in circuit at its front contact 128 the low rcsi.-1tancc winding` 12H to reduce tht` potential. to cause this trunk to test busy at its multiple. .lt is, et course. essential. after thc sel-ctor has so seized an idle trunk, that the low resistance winding oi inc test relay re main in circuit with the test .battery td' occurs while the sequence switch is in posi.`

ticn 3. ll'hen the armature of the test relay 1223 is attracted by the brush i5 engaging the terminals of an idle liuc, it closes the circuit ct' the stop rela-y 131 from battery through resistance 112, test contact 2'., brush 2C). f onductor 1)-1, winding' 131. armature and contact 135 ol' relay 1.213, stop relay lill. sequence switch spring 1.05), to `ground. The armature of relay 131 in pulling up closes the circuit for the motor magnet S1 oi' the sequence switch, and it relays 133 and 131 hold up long enough to allow the contact 101 to close, the sequence switch will more out of position 3 to position 5 under the con trol of its supervisory contact 101. It', how ever-,they do not hold up long,l enough i'or the sequence switch to more out of position 3, the hunting will continue as before. .ly reference `to sequence switch spring 1)'2. it will be noted that the circuit of the high resistance orv test winding oi' 133 is open at the top contact of sequence switch spring S122 after the sequence switch has left position lt' now thc armature o1' the test relay 133 bounds ott' ol' its contacts or is retracted, the circuit of relay 131 will be interrupted and its armature falling' back will open the circuit for the sequence switch motor magnct S1 and close the circuit for the motor magnet 62 of the switch carriage. ln practice. this retraction ot thc armature of relay 1:53 will occur. if at all. prior to thc .sequence switch reaching` titlh position. The circuit for the power magnet 152 will now extend from battery through tho windingr of the power magenl, bach contact and armature of relay 1551, sequence switch contact 11() to ground. The switch carriage is thus driven forward until the finger 7:2 reaches the subnormal contact ll when the circuit will he completed through thc stop relay 131 from battery through resistance 130, lower contact and sequence switch spring;r now clo ed, linger 72. arms 'll, l5, springr 52, wire 5.311, srquencc switch spring 92. and lower contact winding ot relay 131, sequence switch contact 102) lo ground. thus energizing the stop relay and interrupting the circuit of the switch carriage motor magnet, the switch carriage, thus stopping in the subnormal position. The attraction of the armature of gli monaca relay 131 again completati the eireuit for the bequeme siriteh motor magnet Ni as bofore7 which under the tontrol o1 its superviuoi" rontziet lol will more to ita thirteenth po tion, unil thus ihe apparatus will remain with the Switch rnrringe in Suhnorinfil posi-- tion Huil the sequence :enitrh in position thirteen. ,this would iuteiriipi the iz'hu; operutionsz, the ren'iuii'iin ies ot' iiupulxt-wl uhirh uiuler iurnuil mi wouhi serve to return the operntons controller io normal would not he sont. The eontroller useil woulil display :i liuuy giuil or light ais long :is it is luisy,y unil the continued glow ot' this ,uignzil would cle-,note trouble to the op erntor.

To restore the uppnrntusj lo i rontlition, contarte, :541, 'll, 2324T :mil l muy he openeil. rl'he opruiug; oi fournit,

232 :intl relenseg the counting relays h'j opening' their loeul loeltiug en'tzuits. The

opi ningl ol eontnrlS ./'li :uni '135 liseouneiii the stepping relzi)` from the trunk line ri!- cuit` nml this is prefernlvly lione lie/fore the eireuit is usntl for telephonie eonununiimt ion1 rl`he opening o'i eontnrt 2-11 releuses relay V123, whereupon front i-onrzirt, 194.3 openml unil haelt eonl'uri 171%? rlmteil., The elo in, of uninet 125i ronipleles n vit'i'uit foi ih motor muguet N1 of the :ivfpiewe su'iirh hy Mijo!" seilrueneey switch 5;,iiiig' 112 bottoni. Thy se prouve switeh thereupon mlrzintfw to ponir tion 1li.

lll in the rireuit of thu inmoiw'oiii'o. relug; 1131 in opened and :suitl relu): is thereupon lo energized, whereupon its hurk ront-Liet rlosei: :i gzip in the eireuit of the inotor magnet lli/J ol` the seleetor,y the other gap, tontziet. 110. of which is closed when the sequent/ti switch renrhes position 1G. lt should he noted that the tent reludiv 1325 is in rreuit with the motor eoutrol relay 131 nml also heroines de'tner gizetl o tht the path through the low resi.-,t:iure loeltinggY winding' 1371 is now open :it routziet 13.1 :intl the trunk is reiuleretl aree,- sihle to other weleetoru. 'l'he path through the high rcsislriinee winiling' 13:2 huil heroine opened ait sequence snrileh upriup; Sh! top when the sequenou switch pushed out ol' the third position. The switch eau-ringe is inoretl around under tho control ol the niotor nine;- net GQ until it reaches it,` normal positioin whereupon Contact, is nimh hetuetu the lin lrer T22 of lever Y13, :unl the uorouil top plnti 1V. :unl u eireuil, is rloj'eil for the uiuifi wouV trol relay 131. by way of :wipiriu'r riti-h spring Ulf?. the wiluliingr of rrlur i541. sequent-c switch Spring .12 hotioui. eonilueior .l), contuei lever 425, norm-ul stop plute lit si quenoe switeh spring* of top. resiutzu' lll to lmtter'v. The motor w-,ntrol rel-iii' energized in this eirtuit unil opens :it

hurl( Contact, the rirl'uit ol the motor iunet 52. The flor-ing ot' the front mutui-i o.

norin :il

1n coming into pmitiou l1 ront-nrt lutter f-izt'uit her-ing h v wry' of su'teh Spring( 111 bottoni.

rela 1551 ooinpietes circuits hforn, one to illu holdin;r muguet ueotor muguet El of this Suuenee switch, they quenee` The St'iuenee ffiteh thereupon leni'eS position ,1li and re turns: to the, fir# or nornuil position. Upon reiuhing this uoruuil ptsitioni. sequerre suiteh :ioni-(irte. loll 1M and 105, 11,2 top, ttl top :ire again i'zlosetl, and all others .ipezufih plating the apparatus in condition for unother Serief) ot Selecting opeimifms,

lhoulil the operutor (ivoire, after presas-- ing kt 25S. to restore the entire apparatus to normal position immediately, She muy do so lo. merely opening'sequenee switch conti et' "ll Wi; will now consider the resuit of uch emitaet. First', the trunk relay l hr iiiliurfrgizixl and it nruuitin'e, i251 in ret "Listing )uit for the auquenre snit-'h motor nuign'st 8l hy 'way oi sequenre sixii'eh spring' 112 bottoni, whereupon they sequentie h mores from porlitiion '.3 through pim "on 3 und into position I). In thi@l pt tion the 'Striving eirruit including the motor magnet G2, closer! in the thirtl pir sition,

eouinues cloned` and snicl magnet rfiztntre. the hiufih tturringe until thi: Finger ere ii rontnrt 13G asso-friuli@ with they rum 31?, li'e will refer 'to rontnvt. nt lilo me u xuhnoinuil (fout-nit :url the poion ol' the lni i: m fringe when engaging d 'foutiiet, its suhnoruuil position, his -frntairt being ii :stell nezir the end of the i oi' irziwl ot' the wirriugm ln leaving the il pofritioii` the te" circ-,uit was opened :it ser; imfmiteh rapping J2 top so thuiit uns iiup -rihlo for the hrush ezurizfigr to ,stop hetueen its nfiuuuil 'position' null the sulumrnml eonti'ut 13o. 'il' n the inger 72 ('outurhl ith this suluioruml cony et, howewr, rireuit i5 elt'rsei lor the i'elavl'll fr( 'u louter). rrsistuime 13th Seiluenve witch sprinsf fl' hotioiu elosetl in position :3, :fuhuoruizx eontziet 1.315, lever 42S, spring 32, 1, lu for m3. sequent@ Switch sprintf 92 hot- Luni. the izioioi eozitrol relay, rontnet. 1,051 to grou The motor rontrol relay rit its-1 had( vounrt thereupon opens :he :hiring eireuit ol. the Selector :nul :u ith` front eontuet moves 'lu empienee itrh tu position tQhy wily of er'ntuzts lll -iiul lll bottoni in n'liit'h position ine einer switch motor muguet is i-onliuuetl i-:iergm-il hy wir of Soutien 11:? hetloui :unl hawk eontneb ih eoutioi, lltlit being' uoteil thzit the il' tuoi-'ir eontrol relu.)` 131\\':ioprneil l mim: th: equenee swit" e; i ulih pimitou, 'liu' m'iteli rui' i rotated to noinuil, zinfl whrn engugus of: and one, to the4 segment 4G, the circuit previously traced is closed for relay 131 which opens at its back contact the driving circuit and at its front contact moves the sequence switch to normal position. The apparatus is now restored.

y\ttention is now particularly directed to the piovision of an arrangemei'it whereby in case the ripe-out key represented by se tueur-e switch contact 241 is actuated before an, idle trunk has been seized the testing circuit opened to prevent useless subsequent operation; that is, to save time. It will be noted that the test circuit leads through a sequence switch spring 92 top, closed only in the, third or testing position. Assume now it is desired to disestablish the connection after having depressed the stai/ting key.

. It will be remembered that upon the closure of contacts 23T. 23S the line relay 121 became energized and at its front contact and sequence switch 112 top moved the selector sequence switch to position 2. The oflice switch restoring relav l2i is rendered inert by the operation of the key i241, with the result that the sequence switch moves to position 3. lt will be observed now that the sequence switch contact through which cir` cuit was closed to move the sequence switch to this position remains closed in this position and enables the sequence switch to move to position 5. ln position 3 the driving circuit was closed as before to rotate the brush carriage. but since the sequence switch did lnot stop in position 3. but moved immediately to position :7, the testing circuit is open at sequence switch spring 92 top. thuspreventing the seizing of a trunk. and the brush carriage continues rotating until the arm 45 reaches the subnormal contact from which point the restoring operation is the same as hereinbefore recited.

It', for any rea-son, upon the operation of the 'wipe-out key'tlie brush carriage Should be given a slight movement, in accordance with the improvement about to be recited, it cannot remain in such displaced relation as' will now be more particularly described.

lt will be appreciated that should the Sequence switch and other apparatus be restored, except the selector. and notice given the operator that thc equipment is ready for another call, upon the next seizure of this particular switch. and the rotation of its spindle to select the desired set of brushes, the brush carriage not beingr as usual in its normal position. but in close proximity to the spindle. the spindle. when rotated during the brush selecting period, will cause its teeth to trip a number of sets of brushes depending. of course. upon the particular set of brushes desired for that connection. and in the next or trunk hunting period these brushes will, instead of being retracted, engage the line terminals in this movement,7

causing as stated, interference with calls of which multiples of these terminals form a part. This cannot occur with the present system since by the present arrangement it is impossible for the sequence sw itch to move from normal position through its successive periods and restore without a ccrrcsl'ioinling restorative movement of the brush carrie. Te; that is to say. a sort of interlocking arrangement is provided in which the sequence switch having been once moved out of its normal position. must cause a complete revolution of the brush carriage before it can be restored to normal position. lt will be noted that a selector in being restored after having been used in estab ting a successful call docs not stop at this subnormal contact. since the sequence switch is then in position 16 when contact J5 bottom is open.

l claim:

l. The combination with a selector, of ay test brush and fixed terminals adapted to be traversed thereby. means for initially moving Said selector and means voi erned by the electrical condition of any one of said terminals during a portion of the period the test brush is in contact therewith for con trollingr the continued movement of said selector.

In the c-vi'nbination with a selector having test terminals. a test brush and means for causing said brush to t'averse said terminals, and a testi circuit for arresting said brush upon an idle terminal. .said test- Circuit being interrupted during a portion of the` period the test brush is traversing any test terminal.

The combination with a selector. wherein the trunks are represented by liXeo'. terminals whose electrical condition determines their idle or busy condition, thc said fixed tcst terminals. a test brush therefor. powerdriven means for moving saidy brush, ot means for arresting its movement when engaging an idle trunk, and. means for preventing said arresting meansfrom becoming operatne due to a change in the electrical condition of a test terminal while said brush is engaging the latter portion thereof.

4. In combination w'ith a selector` the continuation of whose advance is determined by the electrical condition of the fixed terminals which its test brush engages, the said fixed test terminala and the test brushg of a powershuft. a magnetic clutch for coupling said power-shaft to said brush. and a relay responsive to the electrical condition ot' the tirst portion only of any test terminal for uncovplimgr said clutch.

5. ln combination with a power-driven .trunk hunting switch havingr a test relay for controlling the seizure of idle trunks by-its responsiveness to the electrical condition of their test terminals. and a test brush. with inc-'1111s for initially moving said brushes mcr l Tn witness whereof, I` hercuntu subscribe Suid terminals, means governed by the elecmy nume this 19th day of MarchA. D., 1912. trcul condition cfs-md test terminals for ,l r f v 1 s Q arresting 'their' travel, said means being v DLAIX b IILILVIN' adapted to be actuated only during the pe-A Vilnesses: rod the seid .line brushes are engaging thev WV. F. HOFFMAN, imf part of said line terminals.v O, D. M. Gu'run. 

